Separating process



April l 1924.

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RIDSDALE ELLIS, OF OAK PARK, ILLINOIS, ASSIGNR, BY

Fries..

AND-nastri: selen i,4ss,745

manners, To ELLIS rno'mrron COMPANY, me., or NEW Yonx, N. Y., .a conrosa- 'LION 0F NEW YORK.- y

snrnna'rrne rnoc'nss.

Application led September 17, 1915, Serial No. 51,210.. Renewed November. Q9, 1922.1

To a-ZZ 'whom #may concern.' l Be it known that 1, RmsDALn ELLIS, a citi.- Vzen of the United States, and a resident of Oak Park, in theucounty of .Cook and State.

of Illinois, have invented certain new and useful Improvements in Separating 'Processes, of which the following is a specification.

My invention relatesto processes for concentrating parts of masses of composite character, such as metalliferous ores, by treating the comminuted mass with a gaseous fluid .adapted to aid -in the movement of certain of the comminuted particles rela-l tively to others having different qualities.

More particularly my invention relates to processes for concentrating jmetalliferous ores by means of the preferential afinity of gaseous bubbles for the metalliferous particles, which causes the adhesion of such particles to the bubbles and thereby enables the latter to lift and thereby separate such particles from the other constituents of the ore. The principal objects of myinvention are in general to enhance the efficiency of such separating processes as hithertoy carried out, more particularly by means of gases having certain characteristics, and generally to improve the separation ofv comminuted materials by flotation or Similar means. y

According to the preferred steps of my improved process, I mix the comminuted-material With Water, generate in or otherwise introduce a readily condensable and preferably soluble gas into the ore pulp and then introduce air mechanically, either by injection through a fine orifice or by a itation, int-o the mixture to form a froth whic is collected in any suitable Way.

The readily condensa-ble gas employed maybe of very diverse character, although' the physical and other properties of various gases make certain of them particularly suitable for the purpose l prefer to use'air with additions of such gases as readily condense at an interface.

As a general rule, the readiness with which` a gas will condense upon at an interface detial pressure of the dissolved gases by'usinr an atmosphere ofditferent gas or gases. l therefore, a readily condensable gas is dissolved in the ore pulp it may be partially liberated from solutim b the introduction of air bubbles intothe puip and consequently absorbed at various gas-solid' and 'gas-liq-V uidinterfaces and thereby aid in the separation of the values from the remainder of the ore.'- l A A j The readily condensable gas employed may conveniently be carbon dioxide as it is very cheaply generated either in the pulp or externally thereof, is readily' con-densable, is fairly readily soluble so that it is' adapted for partial pressure reduction processes and being the anhydride of an'acid gives the pulp a slightly acid reaction. `It also possesses a strong natural affinity for metalin a gauge of quartz and slate agitation in an atmosphere of carbon dioxide alone under certain conditions vbetter results were obtained than with air alone. However, superior results' to those attained with either air aloneor carbon dioxide alone were Secured'by saturating the liquid with carbon dioxide'prior to agitation and then agitating in an atmosphere of air.

lt was further found that there is considerable frictional electricity generated where mechanical agitation is employed to introduce. air into the-'pulp and that the efficiency of separation may `be increased by electrically grounding the agitation cell and thereby allowing such electricity to flow away.

ln addition to using certain gases'or mixtures of gases I also prefer to carry out the notation separation in 'the presence of a sof lntion containing 4polyvalent anions and also 1n some cases polyvalent cations for further l increasing the alinity of the gaseousiluids for the `metalliferous particles.

l have found that in general the action of electrolytes is most advantageous when the valence of the anions produced by the solution of such electrolytes is highest, salts ofv tri-basic acids being in general superior to salts'of di-basic acids, and salts 'of quadribasic acids being superior to salts of tribasic acids, and so on.

I have further found that' when no oil is used the best results are generally obtained by usin a neutral or al :aline solut-ion of a salt a apted to give an anion having a rel-v atively high valence in conjunction with a monovalent cation. On the lother hand, when oil is used it is found, under some circumstances, that the best resultsA of all are obtained when a neutral or acid solution of an electrol e is used which is capable of givin cations and anions, both of which are oi igh valence. v

As examples of suitable electrolytes of the first t pe sodium orthophosphate, NasPO, sodi'um pylrophosphate, NaPzO1, and sodium tetrap osphate or tetrametaphosphate, NaeP4O13, may be given.

The results of pyro hosphoric acid appear to yield more qua rivalent anions than orthophosphates do trivalent anions. Consequently I prefer to employ p ophosphates as they give a greater num er of higher valent anions than do orthophosphates.

Similarly sodium pyrophosphate isv superior under certain circumstances to sodium tetraphosphate or `tetrametaphosphate althoue'h the latter is capable of givlng a hexav. l-)ent anion, probably on account of the much lower dissociation of the latter as compared with the former.

As examples of suitable electrolytes of the second type aluminum or titanium pyrophosphate may be given.

It is well known to those skilled in the art that the exact proportions of those substances which may be used in such processes vary somewhat according to the nature of the particular ore treated; therefore, I give, for purposes of illustration, the results of actual practice with theL above referred to cu riferous pyrite ore.

Vith this ore good results were obtained without oil using a solution containing 0.10% (on the ore) of sodium lpyrophosphate or 0.16% of sodium pyrophosphate.

Using oil good results were obtained using a solution containing 0.016% sodium p rophosphate` of 0.01% titanium pyrophosp ate and 0.1% of sulphuric acid.

Various forms of apparatus may be employed for carrying out the separation of metalliferous matter by flotation. One form of apparatus which is suitable for carrying out my process is illustrated in the accon1-` panying drawings, in which Figure 1 is a vertical section through the apparatus as a whole; and

' Figure 2 is a section on the line 2-2 of Fi re 1.

e apparatusv comprises an agitation chamber 5, and'a spitzkasten 6.; In the agiture 13 into the spitzkasten 6, includes particles of metalliferous matter adhering to bubbles of air which raft them to the surface in the spitzkasten to form a layer of' froth 32 atthe top of the water. The agitation chamber is connected to the ground 44 by means of a suitable connection 45.

The tails, consisting of silica, silicates, etc., sink to the bottom of the spitzkasten ,and fcollect in the hopper shaped part 14,

from which they may be transferred by vmeans of a rotary pump 15 and pipe 43 tn a second a itation chamber for further treatment. nly one agitation chamber and spitzkasten are shown, although it is usual to provide a series of such chambers not only for successively treating thetails but also for reiloating the values in order to clean them.

The froth flows over an overflow lip 2() into the launder 31.

The adhesion between the bubbles of rair and the metalliferous particles is not particularly strong in some cases, particularly when no orffanic frothing agent is used, so that there 1s a'tendency for the bubbles to break when they reach the surface of the water and thereb drop the metalliferous particles which ad been attached to them. Acco'rdin ly, I have provided means for collecting t e metalliferous particles which maybe dropped from the surface of the water without interfering with the upward movement of bubbles of air carrying metalliferous particles. Conveniently these means may comprise a number of Vshaped troughs 16 and 17. The troughs- 16 are arranged with their edges overl ing the edges of the trough 17, so that su stantially all particles which fall from the surface by the reaking' of air bubbles will be caught by one or other ofthe troughs 16 or l?. On the other hand a space is provided between the edges of the trou hs 16 and 17, through which the bubbles o air carrying metalliferous particles can Rass on their upward way to the layer of frot The provision of troughs 16 'and 17 below the surface of the water is not in itself suiiicient, as these troughs would soon be filled with metalliferous matter which would then overflow through the spaces between the troughs. Accordingly, I'provide means iis ran ed in the walls of the lfor moving the material which collects in I incline the troughs and also give themv a vibratory to and fro movement so as to shake the material along towards and out of the lower ends. Forvproducing this longitudinal movement of the troughs, I prrovide an eccentric 22 on a shaft'33, driven om the shaft 9 by means. of worm gears 34 and 35. The eccentric 22 is connected by means of a rod 23 to a bell-crank arrangement 24, pivoted at 25 to brackets 26, arranged on each side of the spitzkasten, and connected at its lower end to a crossmember, connected to and carr ing one end of cachot the troughs 16 and l vThe other ends of the troughs are supported b a roller 28, journalled 1n bearingsv29 an 30, ar-

a paratus. T e metalliferous matter 'dbposited in the side chamber 18 is at a lower level than the overow lip 20 and consequently I have provided means for raising it to a height equal to or greater than that of the overliow lip so that such metalliferous matter can be readily discharged separately from the water. I have provided, therefore, an inclined worm conveyor 19 in the side chamber 18. This worm conveyor raises the metalliferous mat I iter to a dischargeeorice 21, whose upper edge is at substantially the same height or higher than the overow' lip 20.

his conveyor may be driven by4 means ofl 'a sprocket 36 on the shaft 33, connected by a claim 37 to a s rocket 38- on an intermediate shaft 39.4 Ihe shaft 39 has a bevel lgear 40, mounted thereon in mesh with a evel gear 41 on the shaft 42 of the worm conve or.

Alt ough in the preferred form of mdy process Y:as above described, the soluble rea ily coifdensable gas is introduced whilst the comminuted ore or other material is suspended in water. The dry comminuted material may, in certain cases, be treated with the readily condensable gas prior to its insertion in the water so that the gas is absorbed on ,the surface of the dry particles.

A ecus uid emplo ed.

While I have referred to the lemployment of-oil as a frothing agent, I may use a soluble organic frothmg agent, such as amyl alcohol.

Finally, I may in some cases em loy heat for aiding in t e separation of t e metalliferous constituents by means of the gas- Y Having thus ascribed 'my invention and sition to ai illustrated itsuse, what I claim is new and desire to secure by Letters Patent is 1. The process of .concentrating composite comminuted masses of composite character which includes mixing the mass withwater, introducing a readily condensable gas comprising the anhydride of an Oxy-acid into the mixture, introducing air into the mixture, and separating the particles of, the mass having a preferential ainity for air from the remainder of the mass by dotation.

2. The process of concentrating composite comminuted masses of. composite character which includes mixing the mass with water, introducing a readily condensable gas havmg a critical temperature above 25 C., comprising the anhydride of an Oxy-acid into.

the mlxture, introducing air into the mixture, andseparating the particles of the mass having a preferential aihnity for air from the remainder of the mass by flotation.

3. The process of concentrating ores which includes mixing the comminuted ore with water to form a pulp, aerating the pulp with bubbles of gas containing carbon dioxide and free oxygen, the percentage of oxygen both free and combined being greater than that of the atmosphere, to form a froth and separating the froth from the remainder by dotation. 4

4. The process of concentrating composite masses of composite character which -includes mixin the mass with water to form a pul intro ucing carbon dioxide and air into t e pulp and separating the particles of the mass having a preferential ainity for airA from the remainder of the mass by flotation.

A 5. The process of concentrating ores which includes mixing the comminuted ore with water 'to form aA gulp, enerating minute bubbles of gas on t e sur ace of the mineral particles in the pulp by reducing-substantially the effective solubility of gases in solution in the water, aeratin the pulp with bubbles of having a ierent compothe first mentioned bubbles to' form a froth with such particles, the

ges forming the froth including in its composition carbon dioxide, and segaratingthe mineral carried bythe froth e om the remainder of the ore. Y.

In testimony whereof I have hereunto sliced. my name in the presence of the two su scrlbing witnesses. 1

y RIDSDALE ELLIS. Witnesses:

PAUL Cenrnmn, v Damm C. Wmnmns. 

